Page type-check: strict's flags that cost nothing, and catch variables as unknown (#235)

why(e) gives a caught error's message; each catch read e.message as any.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/player.ts

@@ -177,7 +177,7 @@ $('#pdead').onclick=async()=>{
   const f=S.feeds.find(x=>x.id===player.feed); if(!f) return;
   const on=!f.deadair;
   try{ await api(`/api/feeds/${encodeURIComponent(f.id)}`,{method:'PATCH',body:JSON.stringify({deadair:on})}); }
-  catch(err){ toast(err.message,true); return; }
+  catch(err){ toast(why(err),true); return; }
   f.deadair=on; paintDead();
   const switched=await switchVersion();
   toast(!on?'DeadAir is off for this show':switched?'DeadAir is cutting the dead air from this show'